JP2002293122A - Speed sensitive type vehicle height adjusting mechanism and controlling method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle height adjusting mechanism capable of stepwise or continuously controlling the height (vehicle height) of a vehicle body according to speed and controlling method therefor. SOLUTION: This mechanism has a speed detection means 6, a leveling valve position moving means 3A, a leveling valve position detection means 4 and a control means 7 for determining a proper vehicle height by map and characteristic drawing prepared in advance based on speed information obtained by the speed detection means 6, determining a proper leveling valve position (LHV) by the proper vehicle height and controlling a leveling valve 3 to move the proper leveling valve position (LHV).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air spring provided on all axes, an air supply means for supplying the air spring, and an air spring interposed in the air supply means for supplying and discharging air to and from the air spring. And a leveling valve for keeping the height of the vehicle constant, and a vehicle height adjusting mechanism having an air spring type shock absorber capable of adjusting the vehicle height.

[0002]

2. Description of the Related Art One of the features of an air spring type shock absorber is an action of maintaining a constant vehicle height regardless of the magnitude of a load. This is performed by a leveling valve interposed in the air circuit that connects the air spring and the air reservoir. The leveling valve body is mounted on the vehicle body and connected to the axle by a connecting rod.

When the load increases (see FIG. 4), a connecting rod CR connected to an axle (not shown) is pushed up, and a lever 3L of a leveling valve 3 connected to the connecting rod CR is pushed up. At this time, since the inlet valve 34 opens and the exhaust valve 35 closes, the air circuit from the air reservoir communicates with the air circuit to the air spring, and air is supplied to the air spring and the height of the air spring increases. I do.

[0004] As the height of the air spring increases, the relative positional relationship between the leveling valve 3 and the mounting position of the air spring on the vehicle body after the load is increased depends on the position of the mounting position of the air spring 3 and the air spring before the load is increased on the vehicle body. It approaches a position equal to the relative positional relationship, and eventually converges to the same relative position. When the levers converge to the same relative position, the lever becomes horizontal, the air supply to the air spring is stopped, and the vehicle body is kept constant.

On the other hand, when the load decreases (see FIG. 3), the lever 3L is pulled down via the connecting rod CR connected to the axle. At this time, the inlet valve 34 is opened, the air circuit from the air reservoir is closed, and the exhaust valve 35 is opened, so that the air on the air spring side is exhausted from the exhaust valve 35 to the atmosphere via the exhaust port 33. . Then, the height of the air spring decreases, and the air spring 3 approaches the position equal to the relative positional relationship between the air spring 3 and the mounting position of the air spring before the load phenomenon, and the air is discharged from the air spring due to the phenomenon opposite to the above. Exhaust) is stopped and the vehicle body is kept constant.

As described above, by always making the internal pressure of the air spring proportional to the load, a constant ride comfort can be obtained regardless of the magnitude of the load, and the vehicle height can always be kept constant.

There are many large sightseeing buses as vehicles equipped with such an air spring type shock absorber. Sightseeing buses have to run on all kinds of road surfaces, such as highways, general urban areas, and sightseeing spots. Therefore, when driving at high speed,
In other words, on highways, to improve high-speed stability,
I want to keep the vehicle height (body) as low as possible with respect to the axle. On the other hand, on uneven terrain such as sightseeing spots, the vehicle height (body)
Want to be as high as possible with respect to the axle. However, in the current bus, there is no vehicle height adjustment mechanism that can cope with the conflicting demands.

[0008]

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above-mentioned conventional problems, and the height (vehicle height) of a vehicle body can be controlled stepwise or steplessly according to the vehicle speed. It is intended to provide a vehicle height adjustment mechanism and a control method.

[0009]

SUMMARY OF THE INVENTION A speed-sensitive vehicle height adjusting mechanism according to the present invention comprises an air spring (1,
2), air supply means (L1, L3) for supplying the air springs (1, 2), and air supply means (L1, L3).
A leveling valve (3) interposed in 3) for keeping the height of the air springs (1, 2) constant by supplying and exhausting air to and from the air springs (1, 2); In a vehicle height adjusting mechanism for a bus having an air spring type shock absorber, a vehicle speed detecting means (6), a leveling valve position moving means (3A), a leveling valve position detecting means (4), and a vehicle speed detecting means are provided. The proper vehicle height is determined based on a map or a characteristic diagram prepared in advance based on the vehicle speed information, and the proper leveling valve position (LHV) is further determined based on the proper vehicle height, and the leveling valve (3) is moved to the proper leveling valve position. (LHV)
And control means (7) for controlling the movement to (1).

The speed-sensitive vehicle height adjusting method according to the present invention comprises air springs (1, 2) provided on all shafts and air supply means (L1, L) for supplying the air springs (1, 2).
3) a leveling valve (3) interposed in the air supply means (L1, L3) and keeping the height of the air springs (1, 2) constant by supplying and exhausting air to and from the air springs (1, 2); A vehicle height adjusting control method for a bus having an air spring type shock absorber capable of adjusting the vehicle height, based on the vehicle speed detecting step (S1) and the vehicle speed information obtained in the vehicle speed detecting step (S1). Step of determining an appropriate vehicle height from a map or a characteristic diagram prepared in advance (S
2) and the appropriate leveling valve position (L
HV) (S3), a leveling valve position (L) detecting step (S4), and an appropriate leveling valve position (LHV) and a current leveling valve position (L) by the control means (7). Determining whether or not the absolute value of the difference is within a predetermined value (α) (S5)
And a step (S6) of moving the leveling valve position (L) to the appropriate leveling valve position (LHV) (claim 2).

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In FIGS. 1 and 2, a pair of air springs 1 is provided on the left and right sides of an independently suspended front shaft FA which is pivotally attached to the vehicle body C and operates independently on the left and right sides, by means not shown in the figure. The rear shaft RA is provided with two pairs of air springs (two in total) on each of the right and left sides, the upper ends of which are fixed to the vehicle body C by means not shown. In the vehicle body C near the air springs 1 and 2, for example, a leveling valve moving actuator driven by a stepping motor 3AC (in the first embodiment, a leveling valve position moving means:
Hereinafter referred to as leveling valve movement actuator)
3A is attached.

The leveling valve moving actuator 3
A is provided with a guide groove 3AG, and a holding member 3B for holding the leveling valve 3 in the guide groove 3AG is configured to be slid (moved) by the leveling valve moving actuator. The holder 3B is provided with an object 3C for indicating the relative position of the leveling valve 3 with respect to the vehicle body C, and a leveling valve position detecting means 4 attached to the vehicle body C side.
Thus, the position of the leveling valve 3 is detected.

The leveling valve 3 has a lever 3L which maintains a horizontal position by a built-in spring when no load is applied. The lever 3L is connected to the front axle FA by a connecting member FA3 by a connecting rod CR.
The rear axle RA is swingably connected to a part of the air spring bracket SB. Although FIG. 2 shows the main part around the rear shaft, the same applies to the front shaft except that the number of air springs is changed from two on one side to one. In FIG. 1, reference symbol FW denotes a front axle, R
A indicates a rear axle, and an arrow EX in FIGS. 1 and 2 indicates exhaust from the leveling valve 3.

The means for supplying compressed air to the air springs 1 and 2 includes an air reservoir 5 communicating with an air generator (not shown) for storing high-pressure air, and an air reservoir 5.
And an air circuit L1 that communicates with the air supply port 31 (see FIGS. 3 and 4) of the leveling valve 3, and a discharge port 32 (see FIGS. 3 and 4) of the leveling valve 3 and the air springs 1 and 2. And an air circuit L3 that communicates with an air circuit connection port that is not used. The movement of the lever L3 of the leveling valve 3 with respect to the variation of the load acting on the axles FA and RA, the flow of air in the air circuit, the movement of the air springs 1 and 2 accompanying the movement of the lever L3 of the leveling valve 3, and the like. The relative positional relationship between the leveling valve 3 and the air springs 1 and 2 is the same as that of the above-described conventional technology, and thus the description is omitted.

In the control system, except for the signal circuit, a controller for controlling a vehicle height adjusting mechanism is provided.
2, a control means; hereinafter, the control means is referred to as a controller) 7; a vehicle speed sensor for detecting a vehicle speed (in claim 1, a vehicle speed detection means: hereinafter, the vehicle speed detection means is referred to as a vehicle speed sensor) 6; And a leveling valve position detecting means 4 for detecting the position of No. 3.

An internal signal circuit of the control system connects the controller 7 and the vehicle speed sensor 6, and inputs an vehicle speed information detected by the vehicle speed sensor 6 to the controller 7.
L6, a controller 7 and the leveling valve position detecting means 4 are connected, an input signal line SL4 for inputting position information of the leveling valve 3 to the controller 7, and a controller 7 and the leveling valve moving actuator 3A are connected. An output signal circuit SL3 for outputting a control signal for causing the controller 7 to move the leveling valve 3 to an appropriate position to the leveling valve movement actuator 3a based on the valve position information and the vehicle speed information.

According to the vehicle height adjusting mechanism of the present invention having such a mechanism, the leveling valve 3 can be freely moved within a range in which the mounting position of the leveling valve 3 with respect to the vehicle body C is set. That is,
In FIG. 2, the position of the leveling valve 3 (height from the center axis of the lever 3L to the lower surface of the vehicle body) is Lmid in a middle speed range such as ordinary city driving, and then the vehicle enters the highway and the speed is reduced. By increasing, the vehicle height is reduced to Lmin by the above-described control, and as a result, the vehicle height also becomes Lmid−Lm.
It drops by in. When the vehicle travels at a low speed such as on uneven terrain, the position of the leveling valve moves to increase the value of L.

Further, according to the position of the leveling valve after being arbitrarily moved at a certain vehicle speed, the position after the movement is set as a reference position and the vehicle height is automatically adjusted so as to maintain the reference position. It becomes possible.

Therefore, the running performance is improved by increasing the vehicle height when traveling on uneven terrain.

At high speeds, running stability is improved by lowering the vehicle height. In addition, by improving the running stability, the fatigue of the driver can be reduced.

Next, a vehicle height adjusting method according to the present embodiment will be described with reference to FIGS. First,
Before describing the control flow in FIG. 6, four patterns (diagrams a to d) showing the relationship between the vehicle speed to be controlled and the vehicle height will be described with reference to FIG. Diagram a
Is the maximum vehicle height H from the vehicle speed 0 to the low vehicle speed Va.
max is maintained and the maximum vehicle speed Vm from the low speed vehicle speed Va
up to ax (linearly with vehicle height H proportional to vehicle speed V)
This is a pattern for lowering to the minimum vehicle height Hmin.

A diagram b shows a vehicle speed Va from a vehicle speed 0 to a low speed.
Until the maximum vehicle height Hmax is maintained and the vehicle speed V
From a to a vehicle speed Vb at a high speed, the vehicle speed is linearly reduced (in proportion to the vehicle speed V to the vehicle height H) to a minimum vehicle height Hmin, and at a vehicle speed higher than that, the minimum vehicle height Hmin is maintained.

The diagram c shows the vehicle height H from the vehicle speed 0 to the maximum vehicle speed Vmax nonlinearly (the vehicle height H is a quadratic function of the vehicle speed).
Is a pattern that goes down.

Diagram d shows the vehicle speed range of low, medium and high speeds.
The vehicle height is divided into Hmax and Hm.
This is a pattern in which the number of steps is reduced to three levels of id and Hmin.

Incidentally, the relation pattern of the vehicle height with respect to the vehicle speed to be controlled is not limited to the above four patterns, but may be set in consideration of the total height of the vehicle, design elements, applications and the proportion of the road to be driven. Good.

The control of the present invention will be described along the control flow of FIG. After starting, in step S1, the vehicle speed sensor 6 detects the vehicle speed, and in step S2, the controller 7 determines an appropriate vehicle height from a prepared map or a characteristic diagram (see FIG. 5). In the next step S3, the controller 7 determines an appropriate leveling valve position LHV from the appropriate vehicle height. Proceeding to the next step S4, each leveling valve position detecting means 4 detects the leveling valve position L.

In the next step S5, the controller 7
Determines whether the absolute value of the difference between the appropriate leveling position LHV and the current leveling valve position L is equal to or less than a predetermined value α. If the value is not equal to or smaller than the predetermined value α (NO in step S5), the process proceeds to step S6, in which the leveling valve 3 is moved by the leveling valve moving actuator 3A in a direction approaching the predetermined value, and the process returns to step S4. If the value is equal to or smaller than the predetermined value α (YES in step S5), the control returns to the original step S1, and repeats the steps from step S1.

According to the vehicle height adjusting method of the present invention including the above steps, the leveling valve 3 can be freely moved within the set range of the mounting position with respect to the vehicle body C.

Further, according to the position of the leveling valve after being arbitrarily moved at a certain vehicle speed, the position after the movement is set as a reference position, and the vehicle height is automatically adjusted so as to maintain the reference position. It becomes possible.

Therefore, when the vehicle is traveling on uneven terrain, the running performance is improved by increasing the vehicle height.

At high speeds, the running stability is improved by lowering the vehicle height. The improvement of the running stability can reduce driver fatigue.

[0032]

The effects of the present invention are listed below. (A) The leveling valve can be freely moved within a range where the mounting position of the leveling valve with respect to the vehicle body is set. (B) According to the position of the leveling valve after being arbitrarily moved at a certain vehicle speed, the position after the movement can be used as a reference position to automatically adjust the vehicle height so as to maintain the reference position. Become. (C) As a result of being able to automatically adjust the vehicle height, the vehicle height is increased when traveling on uneven terrain, and the running performance is improved. (D) At high speeds, the running stability is improved by automatically lowering the vehicle height. (E) Driver fatigue is reduced by improving running stability.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an embodiment of the present invention.

FIG. 2 is a configuration diagram of a main part around a rear axle according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view of the leveling valve, showing a state in which a load acting on an axle decreases.

FIG. 4 is a cross-sectional view of the leveling valve, showing a state where a load acting on an axle increases.

FIG. 5 is a diagram showing a relationship between a vehicle speed and a vehicle height, which is an example of a control pattern according to the embodiment of the present invention.

FIG. 6 is a control flowchart showing control according to the embodiment of the present invention.

[Explanation of symbols]

 1, 2 ... air spring 3 ... leveling valve 3A ... leveling valve movement actuator 4 ... leveling valve position detecting means 5 ... air reservoir 6 ... vehicle speed sensor 7 ... control means, or Controller C: Body FA: Front axle RA: Rear axle L1-L3: Air circuit SL1-SL6: Signal circuit

Claims (2)

[Claims] 1. An air spring provided on all shafts, an air supply means for supplying the air spring, and a height of the air spring being kept constant by supply and exhaust to the air spring interposed in the air supply means. A leveling valve for a bus having an air spring type shock absorber capable of adjusting the vehicle height, comprising: a vehicle speed detecting means, a leveling valve position moving means, a leveling valve position detecting means, Based on the vehicle speed information obtained by the vehicle speed detecting means, a proper vehicle height is determined by a map or a characteristic diagram prepared in advance, and further, a proper leveling valve position is determined by the proper vehicle height, and a leveling valve is set to the proper leveling valve position. Control means for controlling the vehicle to move to a speed-sensitive vehicle height adjustment mechanism. 2. An air spring provided on all shafts, air supply means for supplying the air spring, and a height of the air spring being kept constant by air supply / exhaust to the air spring interposed in the air supply means. A vehicle level adjustment control method for a bus having an air spring type shock absorber capable of adjusting the vehicle height, comprising: a vehicle speed detection step; and a vehicle speed information prepared in advance based on the vehicle speed information obtained in the vehicle speed detection step. Determining an appropriate vehicle height based on the obtained map or characteristic diagram, determining an appropriate leveling valve position based on the appropriate vehicle height, detecting a leveling valve position, and determining whether the appropriate leveling valve position is present by the control means. Determining whether the absolute value of the difference from the leveling valve position is within a predetermined value; and Moving the vehicle to a proper leveling valve position.